What is the difference between ST and LT tires?

Comparing ST and LT Tires: Understanding the Variances

Special Trailer (ST) tires are purpose-built for trailer axle applications, catering to the specific demands of towing without consideration for passenger comfort. Unlike Light Truck (LT) tires, ST tires are engineered to endure heavy loads while being towed behind vehicles. Their reinforced sidewalls prevent rolling under heavy loads during cornering and turning. Traditionally, ST tires boast a maximum speed rating of 65 mph, although recent advancements have seen some models exceed this limit, permitting speeds of up to 81 mph.

In contrast, LT tires are tailored for SUVs, vans, and light pickups, prioritizing both load-bearing capacity and passenger comfort. While LT tires can theoretically substitute for ST tires, they lack the robust sidewall construction crucial for heavy loads. This fundamental discrepancy prompts ongoing debates and occasions where trailers are equipped with LT tires by dealerships. LT tires, offering a stiffer ride compared to passenger tires, are still designed with passenger comfort in mind, unlike ST tires.

The primary contrast between ST and LT tires lies in construction. ST tires incorporate larger polyester or steel cords, ensuring enhanced tensile strength to meet heightened load demands. Additionally, ST tires employ a harder rubber compound with increased sidewall strength and enhanced resistance to aging and UV rays. Conversely, LT tires boast a broader array of tread patterns, although this feature holds little significance when traction isn't a primary concern during towing. ST tire treads are meticulously designed for low resistance, facilitating effortless towing and optimizing fuel efficiency.

Understanding ST Tires: ST, short for "Special Trailer," denotes tires specifically engineered for trailers, eschewing traction and comfort considerations to focus on load capacity and towing stability. These tires feature robust constructions, fortified belt structures, and durable compounds to withstand high load pressures, preventing deformation and enhancing load durability. Their firm sidewalls and consistent surface contact bolster trailer handling and mitigate sway during operation, underscoring the importance of comprehending ST tire specifications for trailer owners.

ST Tire Speed Rating: ST tire options for trailers exhibit limited speed ratings compared to those available for passenger cars and light trucks. This limitation is deliberate, as trailer tire structures prioritize load endurance over heat resistance. Exceeding recommended towing speeds can induce heat accumulation, leading to tire fatigue and potential failure. While modern manufacturing techniques have yielded sturdier ST tires with higher speed ratings of up to 75 mph, it remains imperative for trailer owners to adhere to prescribed speed limits and inflation pressures to ensure optimal tire performance and safety.

The Debate: LT Tires on Trailers? Despite the ongoing discourse regarding the suitability of LT tires for trailers, industry professionals unanimously advise against their use. Unlike ST tires, LT tires lack the requisite sidewall stiffness and structural integrity necessary for towing heavy loads. While LT tires may offer superior heat dissipation, their propensity for deformation under excessive load pressures renders them inadequate for trailer applications. Therefore, to safeguard both the tow vehicle and the trailer, utilizing designated trailer tires remains imperative for free-rolling axles.

Key Disparities Between LT and ST Tires:

  • Trailer tires boast higher load ratings compared to truck tires.
  • Structural durability is significantly enhanced in trailer tires.
  • ST tires feature firmer sidewalls, contrasting with the flexibility of LT tires.
  • LT tires prioritize traction, unlike ST tires, which prioritize load endurance.
  • LT tire sets offer elevated driving comfort levels, whereas ST tires prioritize load capacity over comfort.


Venture Tip: Never substitute light truck (LT) or passenger (P) tires for trailer tires.